| Nowadays,heavy metal pollution has become one of the major potential threats to the environment.Among them,hexavalent chromium?Cr?VI??has a stronger pollution transmission capacity than other metal ions due to its strong solubility and mobility in water,which makes it has a wider range of pollution.In recent years,with the rapid development of electroplating,leather,and other industries,a large number of industrial pollutants containing Cr?VI?are discharged into the environment directly.As a result,the Cr?VI?can enter the human body through the water bodies and the accumulation of food chains,which can bring huge biological damage to the digestive system,liver,kidneys and other organs.There are two traditional treatment methods for Cr?VI?pollution are as follow:one is using physical materials to adsorb and remove Cr?VI?;the other is using biological and chemical techniques to reduce Cr?VI?to t Cr?III?,which is weak in toxicity and migration ability,and then removed by chemical precipitation.Using physical and chemical treatment methods are costlier and more prone to secondary pollution than biological methods.In recent years,Microbial Fuel Cells?MFCs?have received extensive attention as a potential wastewater treatment and bio-capacity technology.To treat Cr?VI?contained wastewater by using biocathode MFC is considered to be a potential advanced technology.However,it is still unable to achieve large-scale practical applications due to the limitations of electrode materials and fuel cell device equipment.Therefore,the development of cathode materials with good biocompatibility,strong electrocatalytic ability,and durability has become a much-needed research direction.In this study,a novel type of wood electrode with anchored silver nanoparticles?Ag NPs Wood Carbon,Ag NPs/WC?was developed and used as a biocathode for a dual-chamber MFC for the first time,which can enhance bioelectricity generation and Cr?VI?remove in catholytes,simultaneously:Firstly,as was characterized by Scanning Electron Microscopy?SEM?,the surface of the pre-acclimatized wood electrode was attached by a large number of Shewanella oneidensis MR-1 and formed a stable biofilm.The MFC can obtain an 8.285±0.253 mW m-2 maximum power density with a Ag NPs/WC biocathode,which is 8.41 times as much as that of biocathode-MFC with traditional carbon felt electrode(0.985±0.008 mW m-2).At the same time,a 98.19±2.01%Cr?VI?removal rate can achieve in catholyte with an initial concentration of 20 mg L-1,when the MFC was equipped with the Ag NPs/WC biocathode,which was significantly higher than other biocathode MFCs equipped with the conventional carbon cloth electrode?48.47±0.84%?,carbon felt electrode?53.31±1.45%?,or no silver particle-anchored Wood Carbon?WC?electrode?88.17±1.92%?;Secondly,as the CV Plots,Tafel Plots,and Electrochemical Impedance Spectroscopy?EIS?test results demonstrated,the surface of Ag NPs/WC biocathode has stronger electrochemical activity,electrocatalytic ability and more non-conductive trivalent chromium precipitate?Cr2O3?rather than other 3 electrodes.Subsequently,Inductively Coupled Plasma Mass Spectrometry?ICP-MS?experiments,X-ray Photoelectron Spectroscopy?XPS?,and Energy Dispersive X-ray Spectroscopy?EDS?were tested,which illustrates that the obtained high Cr?VI?remove rate with Ag NPs/WC biocathode MFC was attributed to catalytic reduction process mediated by silver particles that was acted as an electron shuttle mediator;Lastly,the Ag NPs/WC biocathode MFC had a 70±2 mV maximum voltage and 53.49±0.04%Cr?VI?reduction rate after 3 consecutive batch cycles,which were still significantly higher than 3 other groups of MFC by using control electrodes.These results were also significantly higher than other 3 MFCs using control electrodes.In summary,due to the low cost,strong electrocatalytic activity,and excellent durability of nano-Ag material,this research study used an Ag NPs/WC biocathode MFC to treat the Cr?VI?contaminated wastewater,which can become a new approach with great potential. |
PDF Full Text Request